The advances in technology in the 20th century, particularly in the field of communications, have produced a revolution in electronics, whose influence is being felt worldwide. A representative part of that revolution has been the advent of the personal computer (PC). Personal computers are computers that are meant to be used by individuals in homes or offices. Their retail prices, size, and capabilities make them practical for use in almost every home and office in the United States and other developed countries. The operation of these computers relies on a small computer chip known as a microprocessor, which governs the functioning of the computer.

All PCs have several basic components that allow them to function and be used. The microprocessor controls everything the computer does, and every process has to go through it first. Computers also have memory, both long-term (read-only memory or ROM) and temporary (random-access memory or RAM), as well as data storage. ROM contains the basic software that allows the computer to boot up and generally does not change; RAM is used to store information that the computer is currently working with, such as open programs.

The microprocessor and memory are contained as part of a large circuit board called the motherboard. The motherboard also acts as an intermediary between the microprocessor and other systems on the computer, such as drives and ports. The hard drive or hard disk is where programs and files are stored. As opposed to the RAM, the hard drive has a large capacity and is meant for long-term storage. This is where the majority of data in personal computers is located.

Another important part that is common to all personal computers is the power supply, which regulates the amount of electricity that the PC is using at a given time. Most computers also have sound cards and graphics cards as well, which are small circuit boards that connect to the motherboard to process audio and video data, respectively. Some modern PCs also include a CD-ROM or DVD-ROM drive, where a disk containing programs or files can be inserted. Programs can be run directly from the CD or DVD, which acts as a form of external data storage for a PC.

Personal computers were first introduced on the market in the late 1970s. Their capabilities and speed left much to be desired in comparison with modern PCs, but because of the advancement they represented, their popularity grew quickly, and PCs began to be developed for everyday household use. Computer games and programs were developed which could be used on household computers, further opening up the market for these devices. By the year 2002, one billion had been sold worldwide since they were first introduced.